The present invention relates in general to code alarm circuits, and more particularly to a code alarm circuit producing syllable-pause alarm codes.
Heretofore, Floyd Bell Associates, Inc. of Columbus, Ohio, sold multi-sound alarms, such as Models ML 200 series, that produced a continuous tone, or a continuous tone and beep, or a continuous tone and warble. Thus, one alarm generated more than one distinctive signal. The 2300 series of alarms sold by the same company generated three alarm modes.
The audio signal devices sold by the Cybersonic Division of C. A. Briggs Company of Glenside, Pa., generated distinctive sounds. The Cybertone 4 model generated a yodel, pulsed, continuous or yeow sound. The Cyberblast model generated seven distinct sounds based on various frequency rates and the Barnshee model generated four distinct sounds.
In the patent to Hoerz et al., U.S. Pat. No. 3,872,470, issued on Mar. 18, 1975, for Audible Signal Generating Apparatus Having Selectively Controlled Audible Output, there is disclosed an audible alarm generating circuit in which transistor switching circuits connect a crystal transducer to a direct current supply. The crystal transducer is in series with the crystal transducer. Each transistor switching circuit is controlled by an independent multivibrator oscillator. One oscillator controls one transistor switching circuit in order for the crystal transducer to generate a sound at a given frequency. The other oscillator controls the other transistor switching circuit in order for the crystal transducer to be selectively turned on and off to generate the sound of a given frequency at a pulsing rate.
The patent to Swanson et al., U.S. Pat. No. 4,001,716, issued on Jan. 4, 1977, for Variable Frequency Digital Oscillator discloses a digital oscillator. The output frequency of the digital oscillator is controlled by an output pulse from an output multivibrator circuit. To control the output pulse of the output multivibrator circuit are a plurality of multivibrators with discretely different pulse widths. Period select circuits have voltages selectively applied thereto to gate selectively the plurality of multivibrators for applying the output pulses thereof to the output multivibrator. The multivibrator which is selectively gated for application to the output multivibrator selects the output frequency of the digital oscillator.
The patent to Bench, U.S. Pat. No. 4,000,489, issued on Dec. 28, 1976, for Dual-Mode Waveform Generator discloses a single oscillator operated to generate different audio sounds. The patent to Bench employs a voltage controlled oscillator. The voltage controlled oscillator generates different sounds through the combination of a pulse generator and a step generator.
In the patent to Kawai et al., U.S. Pat. No. 3,686,583, issued on Aug. 22, 1972, for Signal Generator For A Flasher Type Direction Indicator, there is disclosed a signal generator for directional indicating lamps that has a first integrating circuit and a first logic circuit to produce an output signal when operating voltages are applied thereto. In addition, the signal generator includes a second integrating circuit and a second logic circuit to produce an output signal when operating voltages are applied thereto. The output of each logic circuit is coupled to the common inputs of the other integrating and logic circuits so that the indicator lamp is flashed on and off by the output signal of the second logic circuit.
Other patents of interest are: U.S. Patent to Carroll, U.S. Pat. No. 3,930,123; U.S. Patent to Wanless, U.S. Pat. No. 3,735,277.